Die casting machine hydraulic press frequency conversion application control precision more quickly

Foreword

For the die-casting products industry, electricity consumption is the main part of its production cost, and the die-casting machine is one of the main energy-consuming equipment of the product factory, known as the electric tiger. Therefore, reducing the energy consumption of the die casting machine has become an effective way to reduce costs and improve product competitiveness in the die casting industry.

Industry brief

At present, most of the die casting machines belong to the hydraulic transmission die casting machine, and the power in the hydraulic transmission system is provided by the motor driven oil pump. During the change of the die casting cycle, the flow and pressure required by the die casting machine under different processes are different, and the flow valve and the pressure valve must be relied on to adjust the different flow rates and pressures required for different processes. And when the load changes relatively large, because the metering pump can not adjust the output power, the excess energy can only be consumed in the baffle, oil passage leakage, oil temperature rise, and also aggravate the wear of various valves and cause oil temperature. Excessively high, excessive motor noise, and reduced mechanical life. And usually when designing the capacity of the motor is much higher than the actual needs, there is a phenomenon of "large horse-drawn car", resulting in a large waste of electrical energy. Therefore, the promotion of the application of the frequency converter on the die casting machine is of great significance for reducing energy waste.

Process Description

Die-casting machine clamping and demoulding, the oil pressure required for the mold-opening system is low, and the time is short; while the injection, pressure-holding, cooling system requires higher oil pressure and longer time, generally a working cycle of 40 %~60%. The length of each phase is related to the workpiece being processed; the length of the interval is also related to the condition of the workpiece, and sometimes it is not necessary. If the injected screw is driven by a liquid oil motor, the system oil pressure at the time of injection will be higher. The weight of the workpiece processed by the die casting machine ranges from tens of grams to tens of thousands of grams. Therefore, the die-casting machine has small and medium-sized and large-sized parts. The processing time of processing small workpieces of several tens of grams and processing large workpieces of several kilograms is different, that is, for the same die-casting machine, the raw materials of the workpieces are different, each The pressure and time required in the segment process are also subject to change.

Principle of energy saving renovation

According to the working principle of the die casting machine, the high pressure interception is a waste of energy consumption of the oil pump motor. The current vector inverter used in our company's die-casting machine utilizes this feature. According to the requirements of the die-casting machine production process, the inverter is used to adjust the speed of the oil pump motor. According to the pressure or flow parameters required by the die-casting machine and the action of the die-casting machine. The feedback signal synchronously controls the proportional flow valve and proportional pressure valve of the die casting machine to realize the automatic adjustment of pressure and flow. The effect is equivalent to transforming the dosing pump into a variable pump, so that the return flow through the overflow valve is minimized, and the pump output and the whole The pressure and flow required for machine operation are matched and there is no high pressure overflow energy loss. The frequency converter tracks the pressure and flow changes in each working phase through the feedback signal and automatically adjusts the speed of the oil pump motor. In this way, the power consumption of the oil pump motor will change in accordance with the change of the output load, thereby maximizing power saving, that is, economical and practical. Many factories have achieved significant economic benefits through transformation.

Die casting machine power consumption

The power consumption of the die casting machine is mainly reflected in the following parts:

1) Power consumption of hydraulic system oil pump

2) Power consumption of the heater

3) Power consumption of circulating cooling water pump

In the die-casting workshop, generally, a plurality of die-casting machines share a cooling water pump. The power consumption of the hydraulic oil pump motor accounts for more than 80% of the total power consumption of the die-casting machine, so reducing the power consumption is the key to energy saving of the die-casting machine.

Transformation effect

High power saving rate: After the transformation, the quantitative pump becomes an energy-saving variable pump. The hydraulic system of the die casting machine is basically matched with the power required for the whole machine operation. There is no high-pressure throttling and overflow energy loss, and the power saving rate can reach 20%~ 60%.

High efficiency: The power factor before the transformation is generally 0.5-0.8, and it can reach 0.96 or more after the transformation, so it can significantly improve the grid power factor and reduce the reactive current, thus reducing the line loss. For power supply equipment, it plays a role in capacity expansion.

High reliability: keep the original control mode of the die casting machine and the oil circuit unchanged for standby, and promptly report the fault, and have various protections such as overvoltage, overcurrent, overload, overheat, undervoltage and short to ground, etc. Protect the oil pump motor. The utility model adopts the mains/energy-saving operation control mode, and does not affect the production once the fault occurs. Extend the life of the machine and improve the environment: The soft start reduces the vibration of the start-up mode, prolongs the service life of the equipment and the mold, and reduces the noise. Improve the working environment, the system heat is significantly reduced, the oil temperature is stable, and the cooling water consumption can be saved by more than 30%. Extend the life of the seal assembly, reduce downtime maintenance opportunities, and save a lot of maintenance costs.

Soft start energy saving: Since the motor is directly started or Y/Δ start, the starting current is equal to (3-7) times the rated current, which will cause serious damage to the electromechanical equipment and the power supply grid, and will require too much power grid capacity to start. The large currents and vibrations generated are extremely detrimental to the service life of the equipment. After using the variable frequency energy-saving retrofit, the soft start function of the inverter will start the starting current from zero, and the maximum value will not exceed the rated current, which will reduce the impact on the power grid and the requirement of power supply to prolong the service life of the equipment and the mold.

in conclusion

1. Conclusion of intuitive power saving effect

After the power-saving transformation of the die-casting machine, the investment cost can be recovered in only about 6 months according to the lowest power-saving effect, and the service life of the equipment is at least ten years. “Power saving is the fastest investment in the payback period. The longest investment." Users can reduce actual electricity bills, save money, reduce operating costs, and promote business development.

2. Implied economic benefits

According to the power-saving principle of the power saver, in addition to the intuitive power-saving effect, the protection of the equipment and the line will result in prolonging the operating life of the system, the heat generation of the device is small, the operating efficiency is improved, and the maintenance cost is reduced. Investors are also an economic benefit that cannot be ignored. Especially after the power saving reform, the electricity consumption is reduced by 20-40%, which reduces the power loss in the distribution network and improves the power efficiency of the transformer. The hidden economic benefits are also for the investors. A substantial gain.